Single shot reverses rabies

A vaccine that reverses rabies in mice after just one injection may pave the way to cheap, effective prevention of the deadly disease. Current vaccines involve the immediate injection of inactivated viruses and are very effective, but patients need a month-long series of five injections.

Researchers used a live virus that was attenuated (weakened). This stimulates a more powerful immune response, but live viruses can themselves cause disease. By changing a protein on the surface of the virus they could ensure it was safe, but also produce a stronger immune response.

To make sure the genetically modified virus did not cause disease, the team injected the vaccine directly into the brains of mice which were either normal or had weakened immune systems. Neither of the groups of mice showed signs of rabies. They also injected adult mice with a very virulent strain of the virus before giving the vaccine. When the vaccine was given within three days of exposure, the mice did not develop rabies. The vaccine also worked against future infections when injected three weeks before exposure.

There are concerns that an aggressive immune response could cause damage to the nervous system, so further tests will study this aspect in more detail. But there is the prospect of a single injection that could protect people against rabies for life.